The lagoon margin (gronda) is the transition zone between the lagoon and the mainland. It stretches along the entire edge of the lagoon and includes wetlands such as marshes, fishing valleys and embankments. This area plays a crucial role in maintaining the hydrodynamic, ecological and landscape balance of the lagoon system, shaped by the constant interaction between freshwater from rivers and canals and the brackish waters of the lagoon. One of its most characteristic habitats is the reedbed, which provides shelter for many species of migratory and resident birds, as well as for fish and invertebrates. The mixing of fresh and salt water creates an ecotone with particularly high biodiversity, sustaining the biological productivity of the lagoon. The lagoon margin has been shaped by both natural processes and human activity, such as land reclamation and the construction of infrastructure.Its main function is to act as a filter between freshwater and lagoon waters, regulating the flow of sediments and nutrients. Among the areas most heavily modified by human activity in the northern and southern parts of the lagoon are the fishing valleys. These are stretches of water enclosed by embankments and cut off from the tidal cycle, used since antiquity for fish farming. Fishing valleys take advantage of the natural migrations of euryhaline fish, such as gilthead seabream, sea bass and eel, using sluice gates and canals. During the montata in spring and summer, juvenile fish naturally enter the lagoon, drawn by the warmer, food-rich waters, while in autumn and winter the grown individuals make the return journey towards the sea, where reproduction takes place. This natural cycle has been managed for centuries: even today, the most common form of fish-farming in the valleys involves “sowing” them with juveniles caught in the open lagoon, which then grow by feeding on the valley’s natural resources. In the colder months, adult fish are directed towards the sea through sluices that admit colder water, triggering their migratory instinct. They are then intercepted and collected in lavorieri, where fish ready for the market are separated from those destined for winter ponds. The lagoon margin also has great landscape and cultural significance, having been inhabited since the 6th millennium BC. Today, it is the focus of restoration and regeneration projects that aim to make it accessible to the public while enhancing its natural and historical heritage. These include conservation initiatives promoted by WWF and local associations, designed to protect the area, improve access and encourage community participation.

Explore the species of the Lagoon margin

Anas crecca

Argiope bruennichi

Arion rufus

Arvicola italicus

Bufotes viridis

Chelon salien

Circus aeruginosus

Hediste diversicolor

Lucanus cervus

Myocastor coypus

Phragmites australis

Platichthys flesus

Porcellio scaber

Theba pisana

Tritia neritea

Vanessa cardui